U.S. patent number 4,585,298 [Application Number 06/521,191] was granted by the patent office on 1986-04-29 for photoradiator for radiating light.
Invention is credited to Kei Mori.
United States Patent |
4,585,298 |
Mori |
April 29, 1986 |
Photoradiator for radiating light
Abstract
A photoradiator has an elongate light conducting member which is
supplied with converged light at one end thereof. Light radiating
portions are arranged on the light conductor so that the light
propagating through the light conductor may stream out in any
desired light amount distribution along the axis of the light
conductor. The radiating portions comprise spaced annular strips or
spiral strips each being made of a material whose refractive index
is larger than that of the light conductor. A mirror is positioned
at the other end of the light conductor to reflect components of
the incoming light which are substantially parallel to the axis of
the light conductor, thereby promoting efficient radiation of the
incoming light through the radiating portions.
Inventors: |
Mori; Kei (Tokyo,
JP) |
Family
ID: |
26478551 |
Appl.
No.: |
06/521,191 |
Filed: |
August 8, 1983 |
Foreign Application Priority Data
|
|
|
|
|
Aug 26, 1982 [JP] |
|
|
57-148314 |
Sep 3, 1982 [JP] |
|
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57-154448 |
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Current U.S.
Class: |
385/31; 362/551;
385/36 |
Current CPC
Class: |
G02B
6/262 (20130101); G02B 6/001 (20130101); G02B
6/0001 (20130101) |
Current International
Class: |
F21V
8/00 (20060101); G02B 6/04 (20060101); G02B
6/26 (20060101); G02B 6/00 (20060101); G02B
006/00 (); F21V 007/04 () |
Field of
Search: |
;350/96.10,96.28,96.15,96.24 ;362/32 ;D26/3,78,79 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Sikes; William L.
Attorney, Agent or Firm: Jordan and Hamburg
Claims
What is claimed is:
1. Photoradiator comprising:
an elongate light conducting member for conducting converged light
from one end to the other end thereof;
radiating means for radiating the light therethrough to the
ambience radially outwardly of the light conducting member, said
radiating means comprising a plurality of radiating means
positioned at spaced locations along the axis of the light
conducting member; and
reflecting means for reflecting light incident thereon, said
reflecting means being positioned at said other end of the light
conducting member with a reflecting surface thereof faced inwardly
of the light conducting member;
said radiating means being constructed to set up a selective
quantity distribution of the radiated light at least along an axis
of the light conducting member;
said radiating means being constructed such that the total quantity
of light s.sub.i radiated through each of the radiating means after
being introduced into the light conducting member and light s.sub.i
' radiated through said radiating means after being reflected by
the reflecting means, s.sub.i +s.sub.i ', has a specific value
relative to the other radiating means, in which a selected amount
of light S.sub.i to be radiated from the radiating means satisfies
the equation:
where ##EQU12## n is the number of the radiating means, B.sub.i is
a preselected value, and ##EQU13##
2. Photoradiator as claimed in claim 1, in which the reflecting
means comprises a mirror.
3. Photoradiator as claimed in claim 2, in which the mirror is
positioned perpendicular to the axis of the light conducting
member.
4. Photoradiator as claimed in claim 2, in which the mirror is
convex to said one end of the light conducting member.
5. Photoradiator as claimed in claim 2, in which the mirror is
concave to said one end of the light conducting member.
6. Photoradiator as claimed in claim 2, in which the mirror is
inclined relative to the axis of the light conducting member.
7. Photoradiator as claimed in claim 1, in which the reflecting
means comprises said other end of the light conducting member which
is treated for reflection.
8. Photoradiator as claimed in claim 7, in which said other end of
the light conducting member is perpendicular to the axis of the
light conducting member.
9. Photoradiator as claimed in claim 7, in which said other end of
the light conducting member is convex to said one end.
10. Photoradiator as claimed in claim 7, in which said other end of
the light conducting member is concave to said one end.
11. Photoradiator as claimed in claim 7, in which said other end of
the light conducting member is inclined relative to the axis of the
light conducting member.
12. Photoradiator as claimed in claim 1, in which the radiating
means are positioned at distances along the axis of the light
conducting member.
13. Photoradiator as claimed in claim 1, in which the radiating
means are provided with a same radiation coefficient as each
other.
14. Photoradiator as claimed in claim 1, in which the radiating
means comprise annular spaced strips of a light transmitting
material formed on the outer periphery of the light conducting
member, said material being higher in refractive index than the
light conducting member.
15. Photoradiator as claimed in claim 1, in which the radiating
means comprise annular spaced grooves formed in the outer periphery
of the light conducting member.
16. Photoradiator comprising:
an elongate light conducting member for conducting converged light
from one end to the other end thereof;
radiating means for radiating the light therethrough to the
ambience radially outwardly of the light conducting member, said
radiating means comprising a plurality of radiating means
positioned at spaced locations on the light conducting member;
and
reflecting means for reflecting light incident thereon, said
reflecting means being positioned at said other end of the light
conducting member with a reflecting surface thereof faced inwardly
of the light conducting member;
said radiating means being constructed to set up a selective
quantity distribution of the radiated light at least along an axis
of the light conducting member;
said radiating means being constructed such that the total quantity
of light s.sub.i radiated through each of the radiating means after
being introduced into the light conducting member and light s.sub.i
' radiated through said radiating means after being reflected by
the reflecting means, s.sub.i +s.sub.i ', has a specific value
relative to the other radiating means, in which a selected amount
of light S.sub.i to be radiated from the radiating means satisfies
the equation:
where ##EQU14## n is the number of the radiating means, B.sub.i is
a preselected value, and ##EQU15##
17. Photoradiator as claimed in claim 16, in which the radiating
means comprises a plurality of continuous radiating means extending
along the axis of the light conducting member.
18. Photoradiator as claimed in claim 17, in which a total quantity
of light s.sub.i radiated through each of the radiating means after
being introduced into the light conducting member and light s.sub.i
' radiated through said radiating means after being reflected by
the reflecting means, s.sub.i +s.sub.i ', is determined as a
function of the length of the light conducting member measured from
said one end.
19. Photoradiator as claimed in claim 17, in which the radiating
means comprise elongate strips formed on the light conducting
member and made of a material having a larger refractive index than
the light conducting member.
20. Photoradiator as claimed in claim 19, in which each of the
strips extends spirally along the axis of the light conducting
member.
21. Photoradiator as claimed in claim 19, in which each of the
strips extends linearly along the axis of the light conducting
member.
22. Photoradiator as claimed in claim 17, in which the radiating
means comprise grooves formed in the outer periphery of the light
conducting member.
23. Photoradiator as claimed in claim 22, in which each of the
grooves extends spirally along the axis of the light conducting
member.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a photoradiator for effectively
radiating light such as the sunlight to the ambience which is
routed through a fiber optic cable or like light conducting
member.
Effective use of solar energy is the key to energy saving today and
has been studied in various fields actively. For the most effective
use of solar energy, solar energy has to be availed as it is
without being transformed into thermal energy, electrical energy or
like different kind of energy. In light of this, I have made
various proposals for an illumination system which utilizes solar
energy. The illumination system employs a fiber optic cable through
which the sunlight converged by a lens or the like is conducted to
a desired location to stream out thereat to illuminate the
ambience.
In the illumination system of the type described, the light
advancing through the fiber optic cable has directivity. Therefore,
if the light is output at a simple cut end of the cable, it becomes
radiated over an angle which is usually as small as about 46
degrees. The light streaming through the simple cut end of the
cable would fail to evenly illuminate a desired space such as a
room. I have proposed in various forms a photoradiator which is
designed to effectively diffuse light conducted by a fiber optic
cable to provide even illumination over a wide range.
The present invention constitutes a farther improvement over such
predecessors.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a photoradiator
which allows light to be radiated in any desired quantity
distribution in a desired direction along the periphery of a light
conducting member.
It is another object of the present invention to provide a
photoradiator which is capable of effectively radiating to the
outside of a light conducting member even the light components
which propagate through the light conducting member substantially
parallel to the axis of the latter.
It is another object of the present invention to provide a
generally improved photoradiator.
A photoradiator of the present invention includes an elongate light
conducting member for conducting converged light from one end to
the other end thereof. Radiating means radiate the light
therethrough to the ambience radially outwardly of the light
conducting member. Reflecting means is positioned at the other end
of the light conducting member with a reflecting surface thereof
faced inwardly of the light conducting member, thereby reflecting
light incident thereon. The radiating means is constructed to set
up a selective quantity distribution of the radiated light in at
least one direction with respect to the light conducting
member.
In accordance with the present invention, a photoradiator has an
elongate light conducting member which is supplied with converged
light at one end thereof. Light radiating portions are arranged on
the light conductor so that the light propagating through the light
conductor may stream out in any desired light amount distribution
along the axis of the light conductor. The radiating portions
comprise spaced annular strips or spiral strips each being made of
a material whose refractive index is larger than that of the light
conductor. A mirror is positioned at the other end of the light
conductor to reflect components of the light which are
substantially parallel to the axis of the light conductor, thereby
promoting efficient radiation of the incoming light through the
radiating portions.
The above and other objects, features and advantages of the present
invention will become apparent from the following detailed
description taken with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation of a photoradiator embodying the present
invention;
FIGS. 2 and 3 are plots representing operational principles of the
present invention;
FIG. 4 is a view similar to FIG. 1 but showing another embodiment
of the present invention;
FIG. 5a is a side elevation of another embodiment of the present
invention;
FIG. 5b is a section along line b--b of FIG. 5a;
FIGS. 6 and 7 are side elevations of alternative light radiating
means applicable to the present invention; and
FIGS. 8-12 are sections showing various mirror configurations
applicable to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
While the photoradiator of the present invention is susceptible of
numerous physical embodiments, depending upon the environment and
requirements of use, substantial numbers of the herein shown and
described embodiments have been made, tested and used, and all have
performed in an eminently satisfactory manner.
Reffering to FIG. 1 of the drawings, a photoraidator embodying the
present invention includes an elongate transparent light conducting
member 10 made of silica glass or acrylic resin. One end of the
light conducting member 10 connects to one end of a light
conducting cable 12 the other end of which connects to a lens
system (not shown). Light, such as the sunlight, is converged by
the lens system into the cable 12 and routed therethrough to the
light conducting member 10.
A plurality of light radiating members in the form of annular
strips 14.sub.1 -14.sub.n are carried on the light conductor 10 at
spaced locations along the axis of the latter. In this particular
embodiment, four light radiators 14.sub.1 -14.sub.n are shown for
convenience. Each light radiator 14 has a refractive index which is
larger than that of the light conductor 10. A mirror 16 is rigidly
mounted on the other end of the light conductor 10 such that its
reflecting surface opposes the light input end. In this
construction, the light propagates through the light conductor 10
as indicated by an arrow I while being reflected by the periphery
of the light conductor 10 to stream radially outward at the
individual light radiators 14.sub.1 -14.sub.n. The rest of the
light, reached the mirror 16, is reflected thereby to follow the
propagation path backward as indicated by an arrow R, while being
radiated to the outside through the light radiators 14.sub.1
-14.sub.n.
For the description which will follow, the light conductor 10 is
assumed to have a length L and carry the light radiators 14.sub.1
-14.sub.n at spacings l.sub.1, l.sub.2, l.sub.3, l.sub.4 and
l.sub.5. The radiation coefficients of the light radiators 14.sub.1
-14.sub.n are supposed to be l.sub.1, l.sub.2, l.sub.3, and
l.sub.n, respectively.
In accordance with a characteristic feature of the present
invention, an arrangement is made such that light issues through
the light radiators 14.sub.1 -14.sub.n in a desired quantity
distribution along the axis of the light conductor 10, thereby
realizing any desired light distribution curve in illuminating the
ambience.
Referring to FIGS. 2 and 3, the operational principles of the
present invention will be described using the construction shown in
FIG. 1. Constants employed for the description are a total quantity
of light I.sub.0 introduced into the light conductor 10 from the
cable 12, a quantity of light R.sub.0 incident on the mirror 16,
quantities of light s.sub.1, s.sub.2, s.sub.3 and s.sub.4
individually issuing from the light radiators 14.sub.1, 14.sub.2,
14.sub.3 and 14.sub.n without the intermediary of the mirror 16,
quantities of light s.sub.4 ', s.sub.3 ', s.sub.2 ' and s.sub.1 '
individually streaming through the light radiators 14.sub.n,
14.sub.3, 14.sub.2 and 14.sub.1 after being reflected by the mirror
16, quantities of light I.sub.1, I.sub.2, I.sub.3 and I.sub.4
individually reaching the light radiators 14.sub.1, 14.sub.2,
14.sub.3 and 14.sub.4 upon entry into the light conductor 10 from
the cable 12, quantities of light I.sub.4 ', I.sub.3 ', I.sub.2 '
and I.sub.1 ' individually reflected by the mirror 16 to become
incident on the light radiators 14.sub.n, 14.sub.3, 14.sub.2 and
14.sub.1, and a quantity of light I.sub.0 ' reflected by the mirror
16 to return to the light input end of the light conductor 10 where
the cable 12 is located.
Supposing that the radiation coefficients .alpha..sub.1,
.alpha..sub.2 . . . .alpha..sub.n (n=4 in this embodiment) of the
light radiators 14.sub.1, 14.sub.2 . . . 14.sub.n are the same
(represented by .alpha. hereinafter), the quantity of light I.sub.n
reaching any one of the first to "n" light radiators counted from
the cable side is expressed as:
where .sigma. is the absorption of the light conductor 10.
In the same manner, the quantity I.sub.n at the "n" light radiator
14.sub.n is produced by: ##EQU1## Thus, the quantity s.sub.n
radiated from the "n" light radiator is: ##EQU2##
The quantity of light R.sub.0 allowed to reach the mirror 16 in the
above situation is expressed as: ##EQU3##
The light reflected by the mirror 16 propagates backward through
the light conductor 10 toward the light input end. Again, this part
of the light is absorbed by the light conductor 10 or radiated
through the light radiators 14.sub.4, 14.sub.3, 14.sub.2 and
14.sub.1. The quantity of light I.sub.n ' reaching the "n (=4)"
light radiator is obtained as: ##EQU4## where .delta. is the
reflection coefficient of the mirror 16.
Therefore, the quantity of light s.sub.n ' issuing from the "n"
light radiator is:
In the same manner, the quantity of light I.sub.1 ' reaching the
first light radiator 14.sub.1 is produced by: ##EQU5##
The light quantity s.sub.1 ' emanating from the first light
radiator 14.sub.1 is:
The light amount I.sub.0 ' returned to the light input end of the
light conductor 10 is obtained as: ##EQU6##
In the above equations, light attenuation inside the light
conductor 10 may generally be represented by the following
expression: ##EQU7##
In the equations shown above, because all the factors .sigma.,
I.sub.0, .alpha., L, n and the like are known, it is possible to
obtain the individual values s.sub.1, s.sub.2 . . . s.sub.n,
R.sub.0, s.sub.1 ', s.sub.2 ' . . . s.sub.n ' and I.sub.0 ' by
determining relations between s.sub.1 +s.sub.1 ', s.sub.2 +s.sub.2
' . . . s.sub.n +s.sub.n ' inasmuch as the number of unknowns and
that of equations are the same. They in turn will provide the
distances l.sub.1, l.sub.2 . . . l.sub.n between the adjacent light
radiators. Suppose, for example, that light input from the cable 12
into the conductor 10 is radiated by each light radiator by an
amount s.sub.i, light reflected by the mirror 16 is radiated by the
light radiator by an amount s.sub.1 ', and an average amount of
light actually radiated from the light radiators is S. Then, the
light will stream through the individual light radiators in any
desired quantity distribution under the following conditions:
##EQU8## where n is the number of the radiators;
where S.sub.i is a desired (set) quantity of light to issue from a
desired light radiator, and ##EQU9## where .epsilon.<<1 and
on the order of 10.sup.-3, for example.
It will thus be seen that if the spacings between the adjacent
light radiators 14.sub.1 -14.sub.n are selected to satisfy the
conditions stated above, light can be radiated in any desired
quantity from each of the light radiators thereby setting up a
desired light distribution curve along the axis of the light
conductor 10. If desired, the factor B.sub.i may be made zero in
order to emit a same quantity of light from all the light radiators
14.sub.1 -14.sub.n. This would illuminate the ambience evenly with
a same intensity throughout the length of the light conductor
10.
In the above description, a desired light distribution has been
implemented by designing the spacings between adjacent light
radiators as desired, while selecting a common radiation
coefficient for all the radiators. Instead, the radiation
coefficient may be varied from one radiator to another while
forming the radiators at equally spaced positions on the light
conductor 10, in which case the various factors will be expressed
as: ##EQU10##
In conjunction with the above equations, the attenuation of light
inside the light conductor 10 may be expressed as: ##EQU11##
To summarize the embodiment described above, the elongate light
conductor 10 carries thereon a plurality of annular light radiators
14 at spaced locations along the axis thereof. The distance between
adjacent light radiators or the radiation coefficient of each light
radiator may be selected so that any desired light distribution
curve is established along the axis of the light conductor 10. It
will be seen that the radiation coefficient is determined by, for
example, the width of the radiator, i.e. length thereof in the
axial direction of the conductor 10.
Referring to FIG. 4, a second embodiment of the present invention
is shown which is distinguished from the first by a spiral
configuration of light radiators. As shown, a plurality of spiral
strips made of a light radiating material extend throughout the
length of the light conductor 10, two spiral strips 20.sub.1 and
20.sub.2 being shown in the drawing. Again, any desired light
radiation coefficient is achievable for each light radiator
20.sub.1 or 20.sub.2 by selecting a width or a pitch P of each
light radiator accordingly, along the axis of the light conductor
10. The rest of the construction, including the mirror 16, is the
same as in the first embodiment.
if desired, the radiators, whether annular or spiral, may be formed
each in a discontinuous configuration so that the resulting light
distribution becomes uneven in the radial direction of the light
conductor 10 as well.
A third embodiment of the present invention is shown in FIGS. 5a
and 5b. A plurality of light radiators, 22.sub.1 -22.sub.4 extend
individually along the axis of the light conductor 10. As best
shown in FIG. 5b, the light radiators 22.sub.1 -22.sub.4 are spaced
from adjacent ones along the circumference of the light conductor
10. The widths of the light radiators, represented by the width W
of the radiator 22.sub.2, may be so determined along the axis of
the light conductor 10 as to satisfy the equations previously
shown, thereby setting up desired light distributions in the axial
direction of the conductor 10.
While the light radiators described so far have comprised annular
or spiral members each having a refractive index larger than that
of the light conductor 10, their role may be played by annular or
spiral grooves formed in a light conductor, as disclosed in my U.S.
Patent Application Ser. No. 490,685 entitled "Photoradiator And
Method of Producing Same". Such implementations will be outlined
with reference to FIGS. 6 and 7.
In FIG. 6, the elongate light conducting member 10 is formed with a
number of annular grooves 14.sub.1 '-14.sub.n ' at spaced positions
along the axis thereof. In FIG. 7, on the other hand, the light
conducting member 10 is formed with spiral grooves 20.sub.1 ' and
20.sub.2 ' from one end to the other end thereof. It will be
understood that the radiation coefficient may be distributed as
desired by selecting, for example, a specific depth in the case of
the annular grooves or a specific depth or a pitch in the case of
the spiral grooves.
In the foregoing embodiments, the mirror 16 (16') employed for
efficient light radiation has been oriented perpendicular to the
axis of the light conductor 10. Generally, the light routed by the
cable 12 into the light conductor 10 includes components which are
substantially parallel to the axis of the light conductor 10 and
this part of the light is allowed to directly reach the mirror 16
without being reflected by the periphery of the light conductor 10
or, if reflected, a small number of times. Such light components
tends to fail to stream through the light radiators as represented
by the Eq. (12) or (12'). Reference will now be made to FIGS. 8-10
which individually illustrate other embodiments of the present
invention designed to effectively steer even the substantially
parallel components to the ambience of the light conductor 10. In
FIGS. 8-10, no light radiators are shown for the simplicity of
illustration.
The light conductor 10 shown in each of FIGS. 8 and 9 is furnished
with a mirror 16' which is formed convex to the light input end of
the light conductor 10. The conductor 10 in FIG. 10 has a mirror
16' which is suitably inclined relative to the axis of the light
conductor 10. In any of such constructions, substantially parallel
components of light incident on the mirror 16' will become
unparallel to the axis of the light conductor 10 when reflected by
the mirror 16' and, therefore, will be reflected a larger number of
times by the periphery of the light conductor 10 while propagating
toward the light input end. This part of the light is more apt to
break through the light radiators and thereby increase the light
radiation efficiency of the photoradiator, compared to the case
with the perpendicular mirror 16.
Modifications to the mirror configurations described above with
reference to FIGS. 8 and 9 are shown in FIGS. 11 and 12,
respectively. The mirror 16" in FIG. 11 is concave to the light
input end of the light conductor 10 and so is the mirror 16" of
FIG. 12. It will be apparent that the mirrors 16" shown in FIGS. 11
and 12, like the mirrors 16' of FIGS. 8 and 9, effectively reflect
substantially parallel components in different directions so that
this part of the light may also stream through the light radiators
before routed back to the light input end.
In summary, it will be seen that the present invention provides a
photoradiator which, despite its simple construction, realizes any
desired light quality distribution at least along the axis of a
light conducting member and causes even substantially parallel
light components entered the light conductor to be steered
efficiently to the ambience.
Various modifications will become possible for those skilled in the
art after receiving the teachings of the present disclosure without
departing from the scope thereof. For example, the mirror 16 or 16'
for reflecting substantially parallel light components may be
replaced by the end of the light conductor itself where it is
located, if that end is suitably treated to reflect the light
coponents concerned in the same manner. Again, the reflecting end
of the light conductor may be perpendicular or angled to the axis
of the light conductor, or convex or concave to the other or light
input end of the light conductor.
* * * * *